As part of the overall vehicle occupant protection system, seatbelt assemblies have evolved considerably since their earliest inception. Improvements are continually sought relative to durability, ease of manufacturing, and general cost-effectiveness.
One concern that continues to receive attention is the design of the seatbelt pretensioner. Seatbelt pretensioners generally function in concert with an associated retractor to tension and retract a seatbelt during a crash event. Typically, upon a crash event a pretensioner initiator is used to ignite associated propellant thereby actuating the pretensioner and tensioning the seat belt spooled about a seatbelt retractor in rotatable communication with the pretensioner.
State of the art automotive initiators may be described as exhibiting a non-directional output. As a result, upon activation, the hot gases, flame front, and burning particles of the initiator exhibit a radially extending pattern that is somewhat spherical. In these designs, the explosive output of the initiator impacts the performance of the device associated therewith. For example, many pretensioners once activated must be replaced due to the damage caused by initiator operation. In the past, one proven method to address this concern is to increase or decrease the initiator pyrotechnic load, thereby varying the device's output, respectively. This approach, however is quite time-consuming and expensive. An alternative approach responsive to these concerns would therefore be an improvement in the art.